Melt butter in heavy medium saucepan over medium heat. Add onion and sauté until tender, about 8 minutes. Add tomatoes with their juices and chicken broth. Break up tomatoes with spoon. Simmer 30 minutes. Add cream, savory and celery see and bring to simmer. Season to taste with salt and pepper. Stir grated cheese into soup and garnish with parsley and additional grated cheese if desired.